Advances in ascorbic acid (vitamin C) manufacturing: green extraction techniques from natural sources

Ascorbic acid (AA), or vitamin C, is one of the most important vitamins consumed through the diet due to its critical role in many biological processes. Although the human body cannot synthesize it, AA is essential in maintaining healthy bodily structure, acting as a cofactor of many enzymes involved in collagen synthesis and an efficient immune system. At the same time, AA is used in the cosmetic field for its antioxidant and antipigmentary properties, in the food industry as additive, and in chemical synthesis as reducing agent. AA can be chemically synthesized, produced by the oxidative fermentation of bacteria, or extracted from natural sources. This review addresses the most recent developments in its manufacture, including techniques for extracting vitamin C from plants, fruits, vegetables, algae, and leaves, and focusing on the most commonly used green methods, i.e., ultrasound-assisted extraction, microwave-assisted extraction, pressurized liquid extraction, and supercritical fluid extraction. These methods are based on mild extraction conditions, environmentally friendly solvents, low time, cost, and energy consumption. In contrast, their extraction yields are comparable to or even higher than those of conventional methods.